The present invention relates to stent delivery devices and methods and, more particularly, to stent delivery devices having low profiles and predictable positioning capabilities, both rotationally and translationally.
Several problems are associated with known prior art stent delivery devices, particularly ones which are suitable for treating bifurcation lesions. First, they generally have large outer diameters, particularly since the known designs usually include two guidewire lumens—one for a main guidewire and one for a side branch guidewire. The relatively large profiles of currently known systems cause difficulties in maneuverability and access to the site. Furthermore, the presence of two guidewires often results in wire entanglement, making the procedure difficult to perform without multiple insertions and retractions. Another problem which persists in these devices is inaccurate positioning within the vessel. This problem has been addressed with the use of radiopaque markers placed in strategic locations. However, visualization is done in the two-dimensional plane, while the actual procedure takes place within the three-dimensional realm. As such, inaccurate deployment is commonplace, often resulting in either stent jailing or insufficient coverage.
An example of a prior art bifurcation stent delivery system is disclosed in U.S. Pat. No. 6,048,361 to Von Oepen. The system includes a stent with an increased radial opening and a balloon catheter on which the stent is mounted, the balloon catheter having a hollow chamber for passage of a guiding wire so that it exits in a center of the increased opening. The system disclosed therein includes two passageways for guidewires, necessitating a relatively large outer diameter. Furthermore, the presence of two wires can lead to problems of wire entanglement.
Other examples of prior art bifurcation stent delivery systems and methods are disclosed in U.S. Pat. No. 6,692,483 to Vardi et al. and U.S. Publication No. 2001/0049548 to Vardi et al. These include a balloon catheter having a main guidewire lumen and a flexible side sheath having a side branch lumen. The method disclosed aims to reduce wire entanglement by first inserting one of the guidewires, then advancing the system, and finally advancing the second guidewire. Alternatively, one of the guidewires is housed within the system and only released once the system is in place. However, problems of wire entanglement may also occur upon removal of the system. Furthermore, the system disclosed therein is prone to overshooting of the bifurcation, resulting in sub-optimal placement. Finally, the dual lumen configuration results in a relatively large profile for the overall system.
Other similar examples of prior art bifurcation stent delivery systems are disclosed in U.S. Pat. No. 5,749,825 to Fischell et al. and U.S. Pat. No. 6,682,556 to Ischinger. The systems disclosed therein include balloon catheters with side branch tubes, and require two guidewires: one for the main vessel and one for the branch vessel. Similar to the aforementioned prior art, large profile, wire entanglement, and inaccurate positioning are potential problems.
A prior art device which aims to provide improved rotational orientation while avoiding wire entanglement is disclosed in U.S. Publication No. 2003/0055483 to Gumm. Gumm discloses a catheter assembly having a rotatably mounted balloon, and further including a side branch hollow member attached to the catheter balloon. A noted feature of the device is the use of rotating members sealed to opposite ends of the balloon. Thus, the side branch hollow member, the balloon and the rotating members act as a unit which rotates freely relative to the main hypotube. This particular feature is considered an integral part of the design, providing improved orientation of the stent relative to the side branch at the bifurcation. However, this feature also results in an increased overall diameter of the system. Furthermore, it does not provide a way to accurately position the stent in the translational plane.
Attempts have been made to reduce the profile of a single stent delivery device by using a fixed wire balloon catheter, such as is disclosed in U.S. Publication No. 2002/0147491 to Khan et al. The device disclosed therein includes either a short section of guidewire fixedly attached to the distal end of a balloon, or a core wire that extends within the system. This design reduces the profile of the system as compared to prior art devices by eliminating the inner guidewire lumen. However, the system disclosed therein does not teach or suggest the possibility of bifurcation stenting, nor does it provide rapid exchange capabilities.
There is thus a widely recognized need for, and it would be highly advantageous to have, a stent delivery system devoid of the above limitations.